1. Field of the Invention
The present invention relates to a system, server, client, method, and program for detecting whether or not the state of a client matches a predetermined state stored in a server.
2. Description of the Related Art
There are systems in which a server monitors the state of a client, and generates a warning when the state is not in a predetermined state. In this case, the server has to periodically acquire the state of the client, and determine whether or not the state of the client is the predetermined state.
However, when a server periodically acquires and monitors the state of a client, there is a possibility that the state to which the client is transitioning can be estimated on the server side.
Also, there is a method for checking whether or not a string possessed by a client has been accepted by an automaton possessed by a server which is called oblivious automaton evaluation. Oblivious automaton evaluation is a method where the checking process is executed without disclosing the string possessed by the client to the server and without disclosing the automaton possessed by the server to the client. Because the state of the client is oblivious to the server when this checking method is used, the state of the client is not estimated.
However, in oblivious automaton evaluation, the checking process has to be executed each time by returning the automaton to its initial state and transitioning in successive order through the states of the automaton. Therefore, when the state of the client is periodically monitored, the amount of transitioning (processing) increases as time elapses and the processing burden is more substantial.